High Incidence of Occult Atrial Fibrillation in Asian Patients with Cryptogenic Stroke

Background: Occult atrial fibrillation (AF) is not uncommon in patients with stroke. In western cohorts, insertable loop recorders (ILRs) have been shown to be the gold-standard and are cost-effective for AF detection. Anticoagulation for secondary stroke prevention is indicated if AF is detected. The incidence of occult AF among Asian patients with cryptogenic stroke is unclear. Methods: Patients with cryptogenic stroke referred between August 2014 and February 2017 had ILRs implanted. Episodes of AF >2 minutes duration were recorded using proprietary algorithms within the ILRs, whereupon clinicians and patients were alerted via remote monitoring. All AF episodes were adjudicated using recorded electrograms. Once AF was detected, patients were counseled for anticoagulation. Results: Seventy-one patients with cryptogenic stroke, (age 61.9 +/- 13.5 years, 77.5% male, mean CHA(2)DS(2)VASc score of 4.2 +/- 1.3) had ILRs implanted. Time from stroke to the ILR implant was a median of 66 days. Duration of ILR monitoring was 345 +/- 229 days. The primary endpoint of AF detection at 6 months was 12.9%; and at 12 months it was 15.2%. Median time to detection of AF was 50 days. The AF episodes were all asymptomatic and lasted a mean of 77 minutes (+/- 118.9). Anticoagulation was initiated in all but 1 patient found to have AF. Conclusions: The incidence of occult AF is high in Asian patients with cryptogenic stroke and comparable to western cohorts. The combination of ILR and remote monitoring is a highly automated, technologically driven, and clinically effective technique to screen for AF.